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New Results on the Capacity of M-ary PPM Ultra-WideBand Systems

Summary: New Results on the Capacity of M-ary PPM
Ultra- WideBand Systems
J. Zhang, R. A. Kennedy, T. D. Abhayapala
Department of Telecommunications Engineering, RSISE
The Australian National University, Canberra ACT 0200, Australia
Email: jian@syseng.anu.edu.au
Abstract-- In this paper, some new results on the capacity of a
typical M-ary pulse position modulation (M-PPM) time hopping
(TH) Ultra- Wideband (UWB) system are presented. Previous
results using a "pure PPM model" are proven to exaggerate the
real capacity of a UWB system. Based on an extended model
containing correlator and soft decision decoding, the capacity is
evaluated in the single-user case and in the case of a system with
asynchronous multiple user interference (MUI) when the inputs
are equiprobable. It is found that only when bit- signal-to-noise
ratio (bit-SNR) is high enough, larger M leads to higher capacity;
and for a specific M, the optimal values of PPM time offset
parameter Td, which maximize the capacity, are independent
of bit-SNR. The influence of MUI on capacity is detrimental,
especially in the case of high bit-SNR.


Source: Abhayapala, Thushara D. - Department of Information Engineering, Australian National University


Collections: Computer Technologies and Information Sciences